Ac generator for vehicle

ABSTRACT

In An AC generator for a vehicle in which a bearing is inserted into a bearing box formed in a bracket and the bearing is fixed and retained by a retainer, the retainer ( 8, 10 ) has a cylindrical shape and a threaded portion ( 81, 101 ) is formed on the cylindrical section thereof, a threaded portion ( 111, 112 ) is formed on the bearing box, and the threaded portion of the retainer is directly screwed to the threaded portion of the bearing box in order to fix and retain the bearing ( 3 ), so that the gap between the outer circumference surface of the bearing box or the outer circumference surface of the retainer and the opposing side of a cooling fan is made uniform.

TECHNICAL FIELD

The present invention relates to an AC generator for a vehicle that ismounted in a vehicle such as an automobile, a bus, or a truck.

BACKGROUND ART

For example, as disclosed in Patent Document 1, in a conventional ACgenerator for a vehicle, a bearing for supporting a shaft provided in arotor is held by a bracket in such a way that at a retainer, which is afixing plate, a screw is inserted into a retainer thread hole through ascrew through-hole provided in the outer edge of a bracket bearing box.

PRIOR ART REFERENCE

[Patent Document]

-   [Patent Document 1] Japanese Utility Model Application No. 63-23262

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, such a conventional structure has following problems.

(1) Because a cooling fan provided in a rotor supported by a bearingfaces a bracket bearing box, it is required to reduce the size of thebearing in order to avoid the interference between the cooling fan and ascrew through-hole seat at the outer edge of the bearing box; thus, thedurability is deteriorated. In the case where the size of the bearingcannot be reduced, the area of the fan needs to be reduced; thus, thecoolability is deteriorated and hence the output performance and thedurability are affected.

(2) Furthermore, because the screw through-hole seat is provided at theouter edge of the bearing box, there exists a difference between thedistance between the rotor cooling fan and the bearing box and thedistance between the rotor cooling fan and the screw through-hole seatat the outer edge of the bearing box; thus, this difference causes thecooling fan to make a wind sound.

(3) The bracket bearing box and a retainer are fastened by a separatelyprovided screw; however, because there exists a gap between the retainerand the bearing box end face, this structure allows inbound water ordust to intrude into the bearing box.

The present invention has been implemented in order to solve theforegoing problems of the conventional technology; the objective thereofis to provide an AC generator for a vehicle that is characterized by araised bearing durability, a raised output performance, and low noise.

Means for Solving the Problems

In an AC generator for a vehicle in which a bearing is inserted into abearing box formed in a bracket and the bearing is fixed and retained bya retainer, the retainer has a cylindrical shape and a threaded portionis formed on the cylindrical section thereof, a threaded portion isformed on the bearing box, and the threaded portion of the retainer isdirectly engaged with the threaded portion of the bearing box in orderto fix and retain the bearing, so that the gap between the outercircumference surface of the bearing box or the outer circumferencesurface of the retainer and the opposing side of a cooling fan is madeuniform.

Advantage of the Invention

An AC generator for a vehicle according to the present inventioneliminates the screw that has been separately provided to date; thus,the screw through-hole seat on the outer circumference portion of thebearing box can be eliminated and hence the size of the bearing can beincreased without considering the screw through-hole seat. In the casewhere the size of the bearing is left unchanged, the area of the fan canbe increased; thus, because the coolability is raised, the outputperformance of the generator can be raised and the durability can beenhanced due to temperature decrease in the constituent components.

Moreover, the screw through-hole seat on the outer circumference portionof the bearing box is eliminated and the outer circumference of theretainer of the bearing box is made cylindrical, so that the gap betweenthe cooling fan and the bearing box becomes uniform (evenly spaced);therefore, no wind sound occurs and hence the noise level is lowered.Furthermore, the engagement between the male thread on the outercircumference of the retainer and the female thread on the innercircumference of the bearing box makes it difficult for outside water ordust to intrude in the bearing box.

The foregoing and other object, features, aspects, and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating the overall configurationof an AC generator for a vehicle according to Embodiment 1 of thepresent invention;

FIG. 2 is a partial cross-sectional view of the AC generator for avehicle illustrated in FIG. 1;

FIG. 3 is a side view of a front bracket illustrated in FIG. 1;

FIG. 4 is a cross-sectional view illustrating the overall configurationof an AC generator for a vehicle according to Embodiment 2 of thepresent invention;

FIG. 5 is a partial cross-sectional view of the AC generator for avehicle illustrated in FIG. 4;

FIG. 6 is a side view of a front bracket illustrated in FIG. 4; and

FIG. 7 is a partial cross-sectional view illustrating the principalparts of an AC generator for a vehicle according to Embodiment 3 of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be explained withreference to the drawings. In each of the drawings, the same referencecharacters denote the same or equivalent constituent elements.

Embodiment 1

FIG. 1 is a cross-sectional view illustrating the overall configurationof an AC generator for a vehicle according to Embodiment 1 of thepresent invention; FIG. 2 is a partial cross-sectional view of the ACgenerator for a vehicle illustrated in FIG. 1; FIG. 3 is a side view ofa front bracket illustrated in FIG. 1. In each of FIGS. 1 through 3,Reference Numeral 1 denotes a front bracket 1; at the center positionthereof, a bearing box 11 is formed. Reference Numeral 2 denotes arotation axle, and Reference Numeral 3 denotes a bearing that supportsthe rotation axle 2 in a rotatable manner; an inner ring 31 is fit tothe rotation axle 2, and an outer ring 32 is fit to the bearing box 11.Reference Numeral 33 denotes a ball of the bearing 3; two or more balls33 are circumferentially provided. Reference Numeral 4 denotes amagnetic-field iron core fixed to the rotation axle 2; themagnetic-field iron core 4 is configured with a pair of claw-shapedmagnetic poles. Reference Numeral 5 denotes a cooling fan fixed to theside portion of the magnetic-field iron core 4; the cooling fan 5 isformed of a centrifugal fan and functions in such a way as to intakecooling air through an air inlet 1 a formed in the front bracket 1 andto exhaust the cooling air through an air outlet 1 b provided in theouter circumference portion of the front bracket 1. Reference Numeral 6denotes a pulley fixed to the front end of the rotation axle 2; thecrankshaft of an engine drives the pulley 6 through the intermediary ofan unillustrated belt. Reference Numeral 7 denotes a nut for fixing thepulley 6 to the rotation axle 2.

Reference Numeral 8 denotes a retainer for fixing and retaining thebearing 3 in the bearing box 11; the retainer 8 is made of metal such assteel and has a cylindrical shape; a male thread 81 is formed on theouter circumference portion of the retainer 8; in the innercircumference portion thereof, there is formed a nut portion 82, whichis a screwing portion for rotating a screw of the retainer 8 andprotrudes in the shape of an hexagon. The male thread 81 can be screwedto a female thread 111 formed on the bearing box 11. Reference Numeral 9denotes a spacer mounted between the inner ring 31 of the bearing 3 andthe magnetic-field iron core 4.

In the AC generator for a vehicle according to Embodiment 1, configuredin such a manner as described above, when the retainer 8 is mounted, atfirst, the bearing 3 is mounted between the rotation axle 2 and thebearing box 11. After that, the male thread 81 of the retainer 8 isscrewed to the female thread 111 of the bearing box 11 in the axisdirection; then, the hexagonal nut portion 82 of the retainer 8 ispivoted with a wrench or the like, so that the male thread 81 is screwedforward. Then, the retainer 8 is tightened in such a way as to press theside face of the transverse end face of the bearing 3, so that the outerring 32 of the bearing 3 is fixed and held.

The AC generator for a vehicle, configured in such a manner as describedabove, according to Embodiment 1 makes it possible to eliminate theconventional screw for fixing the retainer; thus, the screw through-holeseat on the outer circumference portion of the bearing box 11 can beeliminated and hence the size of the bearing can be increased withoutconsidering the screw through-hole seat. In the case where the size ofthe bearing is left unchanged, the area of the fan can be increased;thus, because the coolability is raised, the output performance of thegenerator can be raised and the durability can be enhanced due totemperature decrease in the constituent components.

The screw through-hole seat on the outer circumference portion of thebearing box 11 is eliminated and the outer circumference of the retainer8 of the bearing box 11 is made cylindrical, so that the gap between thecooling fan 5 and the bearing box 11 becomes uniform (evenly spaced);therefore, no wind sound occurs and hence the noise level is lowered.Furthermore, the screwing between the male thread 81 on the outercircumference portion of the retainer 8 and the female thread 111 on theinner circumference portion of the bearing box 11 makes it difficult foroutside water or dust to intrude in the bearing box 11. On top of that,in the inner circumference portion of the cooling fan 5, the screwingportion of the bearing box 11 and the nut portion 82 of the retainer 8apply a labyrinth action to an intruder through the intake inlet 1 a;therefore, the effect of the intruder in the bearing 3 can be reducedand hence the reliability of the bearing 3 is raised.

Embodiment 2

FIG. 4 is a cross-sectional view illustrating the overall configurationof an AC generator for a vehicle according to Embodiment 2 of thepresent invention; FIG. 5 is a partial cross-sectional view of the ACgenerator for a vehicle illustrated in FIG. 4; FIG. 6 is aside view of afront bracket illustrated in FIG. 4. In each of FIGS. 4 through 6,Reference Numeral 10 denotes a retainer for fixing and retaining thebearing 3 in the bearing box 11; the retainer 10 is made of metal suchas steel and has a cylindrical shape; a female threaded portion 101 isformed at inner side of the outer circumference portion of the retainer10; in the inner circumference portion thereof, there is formed a nutportion 102, which is a screwing portion for rotating a screw of theretainer 10 and protrudes in the shape of an hexagon. The male thread101 of the retainer 10 can be screwed to a male thread 112 formed on theouter circumference portion of the bearing box 11.

In the AC generator for a vehicle according to Embodiment 2, configuredin such a manner as described above, when the retainer 10 is mounted, atfirst, the bearing 3 is mounted between the rotation axle 2 and thebearing box 11. After that, the female thread 101 of the retainer 10 isscrewed to the male thread 112 of the bearing box 11 in the axisdirection; then, the hexagonal nut portion 102 of the retainer 10 ispivoted with a wrench or the like, so that the female thread 101 isscrewed forward. Then, the retainer 10 is tightened in such a way as topress the side face of the transverse end face of the bearing 3, so thatthe outer ring 32 of the bearing 3 is fixed and held.

The AC generator for a vehicle, configured in such a manner as describedabove, according to Embodiment 2 has the same effect as Embodiment 1described above, and the axis-direction protruding dimension of thebearing box 11 can be made shorter than that of Embodiment 1; therefore,the space in the inner circumference portion of the cooling fan 5 canefficiently be utilized, and the axis-direction dimension can bedecreased.

Embodiment 3

FIG. 7 is a cross-sectional view illustrating the principal parts of anAC generator for a vehicle according to Embodiment 3 of the presentinvention. In FIG. 7, Reference Numeral 12 denotes a ring-shaped sealingmaterial that is formed of an elastic body such as rubber and is mountedbetween the right end portion of the female threaded portion 101 of theretainer 10 and the base of the male threaded portion 112 of the bearingbox 11 in the front bracket 1.

In the AC generator for a vehicle according to Embodiment 3, at firstthe sealing material 12 is mounted on the male threaded portion 112 ofthe bearing box 11. After that, the female threaded portion 101 of theretainer 10 is screwed to the male threaded portion 112 of the bearingbox 11 so that the sealing material 12 is compressed and fixed in such away as to be pressed against the right end face of the thread-formedportion of the bearing box 11.

In the vehicle AC generator, configured in such a manner as describedabove, according to Embodiment 3, the sealing material 12 prevents wateror dust from intruding in the screwing portion between the retainer 10and the bearing box 11; therefore, as a matter of course, the durabilityof the screwing portion is raised and the sealing performance for thebearing 3 can be enhanced; thus, the durability of the bearing 3 israised and hence the reliability can be enhanced. In Embodiment 3, asthe sealing material 12, an elastic body such as rubber has beenexemplified; however, a resin or a high-sealing-performance paint may beutilized; furthermore, grease or the like having both a sealing effectand a rust-proof effect may be utilized.

In each of Embodiments 1 through 3, as the shape of the rotating nutportion 82 or 102 of the retainer, a hexagonal shape has beenexemplified; however, it goes without saying that even a tetragonal,pentagonal, or octagonal shape may be allowed.

INDUSTRIAL APPLICABILITY

The present is optimum for an AC generator for a vehicle that is mountedin a vehicle such as an automobile, a bus, or a truck.

DESCRIPTION OF REFERENCE NUMERALS

-   1: front bracket-   11: bearing box-   111: female thread-   112: male thread-   2: rotation axle-   3: bearing-   31: inner ring-   32: outer ring-   33: ball-   4: magnetic-field iron core-   5: cooling fan-   6: pulley-   8, 10: retainer-   81: male thread-   9: spacer-   101: female thread-   82, 102: screwing portion (nut portion) 12: sealing material

1. An AC generator for a vehicle in which a bearing is inserted into abearing box formed in a bracket and the bearing is fixed and retained bya retainer, wherein the retainer has a cylindrical shape and a threadedportion is formed on the cylindrical section thereof, a threaded portionis formed on the bearing box, and the threaded portion of the retaineris directly screwed to the threaded portion of the bearing box in orderto fix and retain the bearing, so that the gap between the outercircumference surface of the bearing box or the outer circumferencesurface of the retainer and the opposing side of a cooling fan is madeuniform.
 2. The AC generator for a vehicle according to claim 1, whereina male thread is formed on the outer circumference of the cylindricalsection of the retainer and a screwing portion for pivoting a screw isformed on the inner circumference portion of the retainer, and a femalethread is formed on the inner circumference of the bearing box.
 3. TheAC generator for a vehicle according to claim 1, wherein a female threadis formed on the inner circumference of the cylindrical section of theretainer and a screwing portion for pivoting a screw is formed on theinner circumference portion of the retainer, and a male thread is formedon the outer circumference of the bearing box.
 4. The AC generator for avehicle according to claim 2, wherein the screwing portion of theretainer has a hexagonal shape.
 5. The AC generator for a vehicleaccording to claim 3, wherein the screwing portion of the retainer has ahexagonal shape.
 6. The AC generator for a vehicle according to claim 1,wherein the retainer is disposed at a portion thereof opposing to theinner circumference of the cooling fan.
 7. The AC generator for avehicle according to claim 3, wherein a sealing material is provided atthe screwing portion between the retainer and the bearing box.
 8. The ACgenerator for a vehicle according to claim 7, wherein the sealingmaterial is formed of rubber.